Radiation detectors have been developed with great excitement for many years. Such radiation detectors are comprised of numerous materials in gas, liquid, and solid state that operate either by generation of electrical charge or photons. While gas and liquid state radiation detectors can be refilled after some level of consumption (i.e., interaction with radiation), no solid state radiation detectors have been developed that can be recharged with an active element or isotope after some level of consumption. This is particularly relevant to neutron detection media, in which the nuclear reaction results in a transformation of the active isotope into another state. Table I shows common thermal neutron (0.025 eV) reactions with various active isotopes of interest.
TABLE IThermal Neutron Absorption Reactions, Q values and Cross Sections.IsotopeReactionQ value (M eV)σth (barns)3He23He + 01n → 13H + 11p0.76453306Li36Li + 01n → 13H + 24α4.78094010B510B + 01n → 37Li + 24α2.310 (94%)38402.792 (6%)157Gd64157Gd + 01n → 64158Gd + γ8.025900conversion electrons (70-182 keV)
Clearly, for the light elements, the reaction transforms the active element into another element, such that over time the detection medium is consumed. It would thus be useful to recharge the active element component of the radiation detector rather than replace the entire device.
Further, while there are passive neutron indicators, such as Thermal Luminescence Detectors (TLDs), that absorb neutrons and are analyzed after some prescribed period of time to determine the energy or amount of effective neutron dose observed, these detectors require processing after the radiation exposure. A simple visual indicator of the presence of or even a range of colors indicating increasing levels of a dose would be of significant utility as a static primary indicator.
In various exemplary embodiments, the present disclosure provides such a rechargeable, solid state, graduated, static primary indicator.